1. Field of the Invention
The present invention relates to a soundproof type water-cooled engine generator which provides such a low-noise structure as improving soundproof performance and cooling efficiency.
2. Description of the Related Art
The conventional cooling structure for this kind of soundproof type water-cooled engine generator, as shown in FIG. 3, includes a water-cooled engine 41, a generator 42, and a soundproof bonnet 43. The water-cooled engine 41 is directly connected to the generator 42 so that they keep their axes aligned. The water-cooled engine 41 and the generator 42 are accommodated in the soundproof bonnet 43. Air inlets 44, 44, 44 are formed on the side wall of the bonnet 43. Those inlets are located close to the generator accommodated in the soundproof bonnet 43. On the opposite side of the water-cooled engine 41 to the generator 42, an engine fan 45 is supported on a shaft contained in the water-cooled engine 41 so that the engine fan 45 is rotated by the engine 41. As opposed to the engine fan 45, a radiator 46 is located. The engine fan 45 is surrounded by an encircling wall 47.
In operation, the engine fan 45 is driven to take air, that is, cooling air from the air inlets 44 to the soundproof bonnet 43. The cooling air is taken inside to cool the generator 42, the water-cooled engine 41, and then the other units such as a battery and a control unit. Then, the air is introduced to an exhaust duct 48 for cooling a muffler located upwardly of the exhaust duct 48. The air is then discharged outside through an exhaust outlet 50. The exhaust duct 48 is formed by partitioning the soundproof bonnet 43 from the shroud chamber where the water-cooled engine 41, the generator 42 and the control unit are held.
Further, another soundproofing and cooling technique has been provided. In this technique, a shroud chamber is independently provided in the exhaust duct 48. A radiator is slopewise located in the front lower portion of a cooling fan provided in the shroud chamber so that the engine fan is spaced from the radiator by a predetermined interval for diminishing a current noise occurring in this radiator.
In the foregoing structure where the radiator is located as opposed to the engine fan, the engine fan is located close to the radiator. Hence, the current noise caused when the cooling current of air given by the engine fan passes through a radiator core is made so large that the noise is guided out of the exhaust outlet through the exhaust duct. The noise guided outside sounds as a large uncomfortable sound around the structure. In particular, such a large sound annoys residents in an apartment house when the engine fan is operated at night.
Moreover, to meet the market demands, the soundproof bonnet is requested to be reduced in size. This leads to reducing the lengthwise dimension of the structure. However, if the front dimension of the radiator is made shorter as keeping the conventional structure, disadvantageously, the resistance against the exhaust current of air is made so large that the cooling performance does not reach the satisfactory level.
As another disadvantage, since the muffler is located upwardly of the exhaust duct without any cover, the muffler serves to directly apply heat to the radiator, thereby lowering the cooling efficiency of the radiator.
In the aforementioned structure where the shroud chamber is independently provided in the outlet of the engine fan and the radiator is simply inclined, the following disadvantages take place. At first, water is reserved in the lower portion than a drain so that water is not allowed to be completely drained out of the radiator. Hence, the radiator holds the air reservoir in the top portion so that the water flow in the radiator is made slow. Second, since the radiator is slopewise located downwardly of the shroud chamber, dirt and oil are likely to adhere to the surface of the radiator core. Third, since the radiator provides its cap in the top, the user needs to take a troublesome operation of pouring water in the radiator.